Puredyne/Live music from a netbook
Live music from a netbook (synths, FX, etc) 
I was using ubuntu on a netbook, really convenient for gigging since it's so small. By default ubuntu is not set up great for realtime-audio or the tiny screen, so I managed to customise it but never managed to get it completely working the way it should. (I tried a few others like ubuntu studio and 64studio too.) Puredyne seems to have fixed pretty much everything I needed - not just the low-latency audio but the slimmed down OS, the selection of software, etc.
I usually use SuperCollider to perform live, with microphone input through a USB audio card, and then various synth sounds and effects from SuperCollider.
I didn't need to do much tweaking to get the live setup working, since the USB sound card worked straight off. I used synaptic to install a few extra programs (such as transset and xcompmgr which allow semi-transparent windows, nice).
JACK is the audio infrastructure, either launched from a script or from the JACK Control program in the menu. The microphone input is straightforward, plug it into my USB soundcard, and make sure the JACK options are set so that it talks to the USB soundcard rather than the built-in one (named "hw1,1" rather than "hw0,0").
I also use Processing sometimes for live graphics, and Audacity to edit recordings...